For a more intuitive approach, the java script tool above shows the theta neuron phase circle, which graphically summarizes the theta neuron properties. Phase varies from -pi to pi. The two fixed circles on the right of the phase circle are the fixed dynamic points which attract or repel the phase, thus causing the phase to change in the absence of any input spikes. Changing the baseline current Io changes the location of these fixed points, and if Io is positive, the fixed points actually merge and dissapear causing the neuron to fire continuously at a fixed frequency. Input spikes cause the phase to jump forward or backward on the phase circle. The amount of this jump depends on the weight and the phase itself. If enough input spikes are given to push the phase over the positive fixed point, then the neuron will eventually spike. Input spikes can be generated with weights w1 or w2 can generated by clicking on the corresponding buttons.